322. 



GARY N. CALKINS 



This history is not followed by the nuclei which degenerate. 

 With them no vesicle is formed, but the daughter nuclei, if they 

 do not degenerate first, form homogenedus massive nuclei which 

 gradually lose their staining capacity and ultimately disappear 

 by absorption. 



62 



Figs. 62 and 63 Intermediate telophase stages of the third division. X 3200. 



Fig. 64 Stage of interchange. The two migrating pronuclei with their attrac- 

 tion spheres,' are passing one another in the anterior fused region. One undi- 

 vided third division nucleus is present in each cell. X 800. 



d. The pronuclei and the interchange. There is no difference 

 in type, although there may be a slight difference in size without 

 significance, perceptible in the two pronuclei formed by this 

 third division. The stationary pronucleus is nearly always in 

 the central region of the cell where it is left after the third divi- 

 sion. The migrating pronucleus, formed at the other pole of the 

 dividing nucleus, is left some 30 m nearer the anterior end. While 



